TallRider

Your question appears to be a cost/benefit question - is it worth spending the extra for butted spokes?

Butted spokes' first advantage is they produce more durable wheels. They're also slightly lighter and slightly less air-resistant, but those are not their major advantages.
The reason that butted spokes produce more durable wheels is that - because of the thinner center sections - they stretch more under a given tension, and thus are less likely to go slack under heavy pedaling or rim deflection from hitting a bump. As such, the elbows and ends are less likely than straight-gauge spokes to get repetitively stressed.

The non-drive-side rear spokes are the ones where this advantage matters most, as those spokes are looser (in a dished wheel) and more susceptible to going slack and compromising the wheel's status as a "pre-stressed structure".
Butted spokes may still be worth something in the rear drive-side and in the front wheel, but that's less likely to come into play. Front wheels are simply under lots less stress, in terms of weight-bearing and dish and torque to turn the wheel.

You're not a heavy rider, and 36 spoke wheels are pretty strong. You may as well build the front wheel with 15g straight-gauge spokes unless you're going to be heavy-touring on it. It's more worth spending money on butted spokes for the rear wheel, especially the rear non-drive-side.

Here's a thread that I recently convened on this topic. Upshot is that butted spokes are helpful everywhere, but they're most especially helpful on the rear non-drive-side.